使用java 的keytool生成RSA 公鑰 私鑰 （含代碼驗證）

keytool的使用
keytool程序由JDK提供，可以生成、查看證書和key.而keystore是key的容器，可以容納多個key及相關信息。
每一條key由一個別名alias引用。可以把keystore中的key導出爲證書文件.cer。顯然，用keytool生成的.cer
是未經CA簽名的證書。

添加一個Key

keytool -genkey -alias acosta -keyalg RSA -keysize 1024 -keystore acosta.keystore

查看keystore中所有的Key

keytool -list -keystore acosta.keystore

查看keystore中指定的一條記錄

keytool -list -v -alias acosta -keystore acosta.keystore

將keystore中的key導出成證書文件

keytool -list -v -alias acosta -keystore acosta.keystore  -export -file acosta.cer

使用java代碼驗證

 代碼如下

RSAUtil.java

package com.cn.costa.testdemo.RSA;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

/**
 * <p>
 * RSA公鑰/私鑰/簽名工具包
 * </p>
 * <p>
 *
 * </p>
 * <p>
 * 字符串格式的密鑰在未在特殊說明情況下都爲BASE64編碼格式<br/>
 * 由於非對稱加密速度極其緩慢，一般文件不使用它來加密而是使用對稱加密，<br/>
 * 非對稱加密算法可以用來對對稱加密的密鑰加密，這樣保證密鑰的安全也就保證了數據的安全
 * </p>
 * 
 * @author wechart
 * @date 2016-4-26
 * @version 1.0
 */
public class RSAUtils {

    public static final String KEY_ALGORITHM = "RSA";                   //加密算法RSA

    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";      //簽名算法

    private static final String PUBLIC_KEY = "RSAPublicKey";            //獲取公鑰的KEY

    private static final String PRIVATE_KEY = "RSAPrivateKey";          //獲取私鑰的KEY

    private static final int MAX_ENCRYPT_BLOCK = 117;                   //RSA最大加密明文大小

    private static final int MAX_DECRYPT_BLOCK = 128;                   //RSA最大解密密文大小

    /** 
     * <p>
     * 生成密鑰對(公鑰和私鑰)
     * </p>
     * 
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }

    /**
     * <p>
     * 用私鑰對信息生成數字簽名
     * </p>
     * 
     * @param data 已加密數據
     * @param privateKey 私鑰(BASE64編碼)
     * 
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64Utils.encode(signature.sign());
    }

    /**
     * <p>
     * 校驗數字簽名
     * </p>
     * 
     * @param data 已加密數據
     * @param publicKey 公鑰(BASE64編碼)
     * @param sign 數字簽名
     * 
     * @return
     * @throws Exception
     * 
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64Utils.decode(sign));
    }

    /** *//**
     * <P>
     * 私鑰解密
     * </p>
     * 
     * @param encryptedData 已加密數據
     * @param privateKey 私鑰(BASE64編碼)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /** *//**
     * <p>
     * 公鑰解密
     * </p>
     * 
     * @param encryptedData 已加密數據
     * @param publicKey 公鑰(BASE64編碼)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /** *//**
     * <p>
     * 公鑰加密
     * </p>
     * 
     * @param data 源數據
     * @param publicKey 公鑰(BASE64編碼)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 對數據加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * <p>
     * 私鑰加密
     * </p>
     * 
     * @param data 源數據
     * @param privateKey 私鑰(BASE64編碼)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * <p>
     * 獲取私鑰
     * </p>
     * 
     * @param keyMap 密鑰對
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

    /**
     * <p>
     * 獲取公鑰
     * </p>
     * 
     * @param keyMap 密鑰對
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

   public static PublicKey loadPublicKeyByFile(String filepath) throws Exception {  
       try {  
           //通過證書,獲取公鑰
           CertificateFactory cf = CertificateFactory.getInstance("X.509");
           Certificate c = cf.generateCertificate(new FileInputStream(filepath));
           PublicKey publicKey = c.getPublicKey();
           return publicKey;
       } catch (IOException e) {  
           throw new Exception("公鑰數據流讀取錯誤");  
       } catch (NullPointerException e) {  
           throw new Exception("公鑰輸入流爲空");  
       }  
   }

   public static PrivateKey loadPrivateKeyByFile(String filepath, String alias, String password) throws Exception { 
       try {
           KeyStore ks= KeyStore.getInstance("JKS");
           ks.load(new FileInputStream(filepath), password.toCharArray());              

           PrivateKey privateKey = (PrivateKey)ks.getKey(alias, password.toCharArray());    
           return privateKey;
       } catch (IOException e) {
           throw new Exception("私鑰數據讀取錯誤");
       } catch (NullPointerException e) {
           throw new Exception("私鑰輸入流爲空");
       }
   }

    public static void main(String[] args){
        String serverAlias = "";
        String clientAlias = "acosta";

        String serverPassword = "";
        String clientPassword = "acosta";

//      String serverPrivateKey = "d:\\server.keystore";
//      String serverPublicKey = "d:\\server.cer";  

        String clientPrivateKey = "E:\\TestCER\\RSATest04\\acosta.keystore";
        String clientPublicKey = "E:\\TestCER\\RSATest04\\acosta.cer";  
//      
//      String serverPublicString = "";
//      String serverPrivateString = "";
        String clientPublicString = "";
        String clientPrivateString = "";


        String orgString = "{\"ret\":\"0\",\"ExpireTime\":\"2015/10/28 23:59:59\",\"rettxt\":\"OK\",\"Token\":\"69296128A59798E2D423D3B1A9F766F4\"}'";

        String encryptString = "";
        String decryptString = "";

//      RSAPublicKey srvPubKey = null;
        RSAPublicKey cltPubKey = null;
//      RSAPrivateKey srvPriKey = null;
        RSAPrivateKey cltPriKey = null;

        try{        
            //1- 客戶端公鑰      
            cltPubKey = (RSAPublicKey) RSAUtils.loadPublicKeyByFile(clientPublicKey);

            //2- 客戶端私鑰
            cltPriKey = (RSAPrivateKey) RSAUtils.loadPrivateKeyByFile(clientPrivateKey, clientAlias, clientPassword);

//          //3- 服務端公鑰
//          srvPubKey = (RSAPublicKey) RSAUtils.loadPublicKeyByFile(serverPublicKey);
//          
//          //4- 服務端私鑰
//          srvPriKey = (RSAPrivateKey) RSAUtils.loadPrivateKeyByFile(serverPrivateKey, serverAlias, serverPassword);

            System.out.println("\nclientPublicString:\n"+Base64Utils.encode(cltPubKey.getEncoded())+"\n");
            System.out.println("\nclientPrivateString:\n"+Base64Utils.encode(cltPriKey.getEncoded())+"\n");
//          System.out.println("\nserverPublicString:\n"+Base64Utils.encode(srvPubKey.getEncoded())+"\n");
//          System.out.println("\nserverPrivateString:\n"+Base64Utils.encode(srvPriKey.getEncoded())+"\n");         
        }catch(Exception e){
            e.printStackTrace();
        }

//      System.out.println("\n=============================== Step-1:客戶端私鑰加密-服務端公鑰解密\n");
//      //客戶端私鑰加密-服務端公鑰解密
//      try{            
//          byte[] data = orgString.getBytes();
//          
//          byte[] encodedData = RSAUtils.encryptByPrivateKey(data, Base64Utils.encode(cltPriKey.getEncoded()));            
//          encryptString = new String(encodedData);            
//          
//          byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, Base64Utils.encode(srvPubKey.getEncoded()));
//          decryptString = new String(decodedData);
//          
//          System.out.println("orginalString:"+orgString);
//          System.out.println("encrypString:"+encryptString);
//          System.out.println("decryptString:"+decryptString); 
//      }catch(Exception e){
//          System.err.println("Step-1 解密失敗!");
//      }
//      
//      System.out.println("\n=============================== Step-2:服務端私鑰加密-客戶端公鑰解密\n");
//      //服務端私鑰加密-客戶端公鑰解密
//      try{
//          
//          
//          byte[] data = orgString.getBytes();
//          
//          byte[] encodedData = RSAUtils.encryptByPrivateKey(data, Base64Utils.encode(srvPriKey.getEncoded()));            
//          encryptString = new String(encodedData);        
//          
//          byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, Base64Utils.encode(cltPubKey.getEncoded()));
//          decryptString = new String(decodedData);
//          
//          System.out.println("orginalString:"+orgString);
//          System.out.println("encrypString:"+encryptString);
//          System.out.println("decryptString:"+decryptString); 
//      }catch(Exception e){
//          System.err.println("Step-2 解密失敗!");
//      }

        System.out.println("\n=============================== Step-3:客戶端私鑰加密-客戶端公鑰解密\n");

        String orgString2 = "";
        //客戶端私鑰加密-客戶端公鑰解密
        try{            
            byte[] data = orgString.getBytes();

            byte[] encodedData = RSAUtils.encryptByPrivateKey(data, Base64Utils.encode(cltPriKey.getEncoded()));            
            encryptString = new String(encodedData);            

            byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, Base64Utils.encode(cltPubKey.getEncoded()));
            decryptString = new String(decodedData);

            System.out.println("orginalString:"+orgString);
            System.out.println("encrypString:"+encryptString);
            System.out.println("decryptString:"+decryptString); 
        }catch(Exception e){
            System.err.println("Step-3  解密失敗!");
        }
//      
//      System.out.println("\n=============================== Step-4:服務端私鑰加密-服務端公鑰解密\n");
//      //服務端私鑰加密-服務端公鑰解密
//      try{            
//          
//          byte[] data = orgString.getBytes();
//          
//          byte[] encodedData = RSAUtils.encryptByPrivateKey(data, Base64Utils.encode(srvPriKey.getEncoded()));            
//          encryptString = new String(encodedData);        
//          
//          byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, Base64Utils.encode(srvPubKey.getEncoded()));
//          decryptString = new String(decodedData);
//          
//          System.out.println("orginalString:"+orgString);
//          System.out.println("encrypString:"+encryptString);
//          System.out.println("decryptString:"+decryptString); 
//      }catch(Exception e){
//          System.err.println("Step-4 解密失敗!");
//      }
//          
   }

}

Base64Utils

package com.cn.costa.testdemo.RSA;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import Decoder.BASE64Decoder;
import Decoder.BASE64Encoder;



/** *//**
 * <p>
 * BASE64編碼解碼工具包
 * </p>
 * <p>
 * 依賴javabase64-1.3.1.jar
 * </p>
 * 
 * @author wechat
 * @date 2014-5-19
 * @version 1.0
 */
public class Base64Utils {

    /** *//**
     * 文件讀取緩衝區大小
     */
    private static final int CACHE_SIZE = 1024;

    /** *//**
     * <p>
     * BASE64字符串解碼爲二進制數據
     * </p>
     * 
     * @param base64
     * @return
     * @throws Exception
     */
    public static byte[] decode(String base64) throws Exception {
        BASE64Decoder decoder = new BASE64Decoder(); 

        try { 
            return decoder.decodeBuffer(base64); 
        } catch (Exception e) { 
            return null; 
        } 

    }

    /** *//**
     * <p>
     * 二進制數據編碼爲BASE64字符串
     * </p>
     * 
     * @param bytes
     * @return
     * @throws Exception
     */
    public static String encode(byte[] bytes) throws Exception {
        BASE64Encoder encoder = new BASE64Encoder();
        return new String(encoder.encode(bytes));
    }

    /** *//**
     * <p>
     * 將文件編碼爲BASE64字符串
     * </p>
     * <p>
     * 大文件慎用，可能會導致內存溢出
     * </p>
     * 
     * @param filePath 文件絕對路徑
     * @return
     * @throws Exception
     */
    public static String encodeFile(String filePath) throws Exception {
        byte[] bytes = fileToByte(filePath);
        return encode(bytes);
    }

    /** *//**
     * <p>
     * BASE64字符串轉回文件
     * </p>
     * 
     * @param filePath 文件絕對路徑
     * @param base64 編碼字符串
     * @throws Exception
     */
    public static void decodeToFile(String filePath, String base64) throws Exception {
        byte[] bytes = decode(base64);
        byteArrayToFile(bytes, filePath);
    }

    /** *//**
     * <p>
     * 文件轉換爲二進制數組
     * </p>
     * 
     * @param filePath 文件路徑
     * @return
     * @throws Exception
     */
    public static byte[] fileToByte(String filePath) throws Exception {
        byte[] data = new byte[0];
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = new FileInputStream(file);
            ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                out.write(cache, 0, nRead);
                out.flush();
            }
            out.close();
            in.close();
            data = out.toByteArray();
         }
        return data;
    }

    /** *//**
     * <p>
     * 二進制數據寫文件
     * </p>
     * 
     * @param bytes 二進制數據
     * @param filePath 文件生成目錄
     */
    public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {
        InputStream in = new ByteArrayInputStream(bytes);   
        File destFile = new File(filePath);
        if (!destFile.getParentFile().exists()) {
            destFile.getParentFile().mkdirs();
        }
        destFile.createNewFile();
        OutputStream out = new FileOutputStream(destFile);
        byte[] cache = new byte[CACHE_SIZE];
        int nRead = 0;
        while ((nRead = in.read(cache)) != -1) {   
            out.write(cache, 0, nRead);
            out.flush();
        }
        out.close();
        in.close();
    }


}

需要jar包

sun.misc.BASE64Decoder.jar
FastInfoset.jar